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.(No Model.) 2 Sheets--Sheet 1. F. M. STEVENS. Steam Generator.

Patented Sept. 28, 1880.

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(No Model.)

F. M. STEVENS. Steam Generator.

Patented sept. 28,1880.

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INVENTDR @rvu/vd@ ATTESTI N. PETERS. PHOTO-UIHOGRAPHER, WASHINGTUN. D C.

Unirse Stearns Parana* rrrcn.

FRANK M. STEVENS, OF CONCORD, N. H., ASSIGNOR OF ONE-HALF OF HIS RIGHT T() JOHN H. PEARSON; SAID PEARSON ASSIGNOR OF -ONE-HALF OF HIS RIGHT TO CHARLES C. PEARSON, ALL OF SAME PLACE.

STEAM-GENERATOR.

SPECIFICATION forming part of Letters Patent No. 232,773, dated September 28, 1880.

Application iilcd March 23, 1880. (No model.)

To all whom zt may concern:

Be it known that I, FRANK M. STEVENS, of Concord,in the county of Merrimack and State of New Hampshire, have invented certain Improvementsin SteainGenerators, of which the following is a full, clear, and exact descrip tion.

My improved generator or boiler may be employed for the economical generation of steam 1o for all purposes; but, as herein shown, it is especially adapted to be employed on locomotives in lieu ofthe ordinary horizontal tubular boiler.

The improvements relate partly to the con struction and arrangement oi' the hre-box and combustion-chamber, partly in the form and construction of the boiler-shell, and partly in the construction and arrangeinentot the compound pendent water-tubes and the stay-bolts 2o ot' the boiler-shell.

In the drawings which serve to illustrate my invention, Figure l is a longitudinal vertical 1nid-section of my improved generator. Fig. 2 is a transverse section of the same,

taken in the plane of line .z in Fig. l. Fig.

3 is a plan ofthe same, the generator'shell being removed from the right-hand end, so as to reveal the interior ofthe furnace. Fig. 4. is a plan, and Fig. 5 an elevation, of a jet appa- 3o ratus for introducing steam into the stack. Fig. 6 is a vertical mid-section of one of the compound water-tubes, and Fig. 7 is a transverse section of the same, taken in the plane of the line y y inFig. G. The last four ligures 3 5 are drawn to a scale double that of the first three figures.

Let A represent the tire-box, which may be provided with a grate, a, an ash-pan, b, and a lire-door, c, in the usual way. B is acombus- 4o tion-chamber, which opens out of the lire-box and extends forward to the stack or uptake C.

'The entire inner faces of the lire-box and combustion-chamber are lined with ire-brick d, or other equivalent refractory material.

D is the boiler-shell, which is made from boiler-plate, and preferably of two concave flanged halves, joined together at the horizon- 'tal median line by means of rivets, as shown.

All of the hollow of the shell might be formed in one of the parts and the other part be hat; 5o but for strength, convenience of manufacture, and cheapness I prefer to form hall' the hollow of the shell in each part, liange the edges, and join them together, as shown. This boilershell rests directly upon the walls of the irebox and combustion-chamber, and the interstices between the tire-brick and the boilershell are illed in with fire-clay or other refractory material, as indicated at c e in the figures, so as to prevent the air from entering 6o at the joint between them.

The boilershell being broad, dat, and thin, it will require to be properly stayed, and I provide for this, in connection with compound water-tubes arranged to depend from the lower 6 5 or tube sheet of the shell, as will now be described. In Figs. 6 and 7 I have shown the compound tube and stay enlarged.

E is a thin metal tube closed at the bottom and attached at the top to a tubular cast-metal 7o nut, F. This nut is provided with a squared or polygonal portion, j', toreceive awrench,ascrew threaded portiolng, to screw into the tube-sheet or shell, and an elongated tubular portion to form a nut to receive the stay-bolt h, and an inner tube, i. The stay-bolt may be threaded throughout its entire length, and be made conical at its top, and when it is screwed down through the crown-sheet of the boiler it engages the bore of the nut, which is internally screw- 8o threaded to receive it.

To make a close joint a washer or gasket, j, of copper or some other suitable material, may be inserted under the head or" the stay-bolt, if necessary. The inner tube, t', screws into the 85 tubular nut at 7c, and the lower end is free and open. An opening, l, is made through the nut above the end of the tube fi, and another,

m, is made through it below the point k. These openings may be of any size or shape, 9o and serve to permit the circulation of water through the tubes.

In putting in my compound tube the parts E F and h and z' are made in separate parts. The tubei is inserted and screwed in from be- 9 5 low. The outer tube, E, isinserted in its socket and brazed in place. The compound tube is then screwed into the tube-sheet, and the staybolt lb screwed down into the nut and through the crown-sheet until its head rests firmly on the said sheet. By this construction I am enabled to employ the thinnest possible material for the tribe E consistent with strength, and the heat imparted to the said tube and the exposed part f of the nut F is conducted, by the internal parts ofthe nut and the stay-bolt h, to the water in the boiler.

The arrows in Fig. 6 show the circulating travel of the water. Entering the upper end ofthe tube i through the aperture l, the water descends to the bottom of the tube E. There it is heated and rises around the inner tube, passing out at the aperture m into the boilershell again. By this means a constant circulation is kept up through all the tubes.

Although but few tubes are shown in the drawings, I may, and generally do, employ a large numberin practice. In a full-sized boiler for a locomotive more than tive hundred tubes will be employed, arranged close together and staggered, as indicated in Figs. 1 and 2, so

'that the tubes of one row across the combustion-chamber ma-y cover the spaces between those in the adjacent rows. Thus the iianies and heated gases are caused and compelled to impinge forcibly against allot' the tubes on their way to the uptake, the said tubes being arranged directly across their path. The close order of the tubes and their peculiar arrange ment has a somewhat retarding effect on the gases, and prevents, in a good degree, the escape of any of the unconibined gases to the stack, and insures perfect combustion. The tubes should reach down nearly to the floor p of the combustion-chamber.

To insure the most intense heat in the rebox and combustion-chamber from end to end, I avoid all water-spaces around the sa1ne,which serve to lower the temperature of the gases7 and line the whole interior surface ofthe iire-box and combustion-chamber with tire-brick or other G is the steam-pipe leading to the engines.

This serves as a steam-drum also, and is mounted on several short hollow legs, au. By thus providing the pipe with more than one inlet from the boiler I prevent priming to a great extent.

The method heretofore usually employed on locomotives for obtaining draft while under way has been to exhaust from the cylinder into the stack. The force of the exhaust-steam isinjurious, as it causes nearly all the trouble arising from sparks, and the wear and tear on the interior parts of the stack are very great.

Isupply the jet of steam to the stack by means of the following-described mechanism H is a steam-pipe,which,bypreference,tapstheboilershell at or near the rear end of the boiler, and as low down as possible, so that the valve q, which controls it, may be within the reach of the tirema'n. This pipe H leads forward to the stack, which it taps at i" in Fig. 1. On the inner end of the pipe, which is arranged in the axis of the stack and is directed upward, is mounted a jetring, s. This ring is tubular, and is provided with regularly-arranged perforations in its upper face, as shown in Figs.4 and 5, and it is connected with the pipe II by means of supportin gpipes t t. The jet-rin g s supplies the steam to the stack in equally-distributed jets, and the streams cominingle and expand just above the ring, iilling the entire area of the stack and producing the proper vacuum by the upward movement. I thus obtain the maximum of effectiven ess with the least expenditure of steam, and with the expenditure of very little injurious force upon the stack.

The water is introduced into the generatorshell at u, and the blow-off pipe c is arranged at the opposite end.

The shell D is secured to the outer casing by means of angle-irons on the casing and corresponding angle-irons secured to the shell. I prefer to employ four, one at each end and one at each side, and to slot the bolt-holes, so as to permit of both lateral and longitudinal expansion and contract-ion.

Air may be admitted to the fire-box above the grate by means of apertures w fw, as shown.

As indicated in Fig. 2, the walls of the iirebox and combustion-chamber are widened or extended laterally above the bottom of the said chamber, whereby I ain enabled to employ a wider boiler-shell and to get in a greater number of tubes than would be possible if the walls were carried up parallel with the sides of the fire-box. The latter ymust be narrow enough to drop between the drivers of the locomotive.

To cause the ianies and gases to be deflected upward into or among the tubes, I place at the angle formed by the back wall of the firebox with the iioor p of the eombustion-cham ber a detlector, a. This prevents the flames from passing back along the floor of the chamber B. l may or may not extend the tubes down close to the said door; but I prefer to leave a few inches of space below them, to give room for clearing out soot or ashes that may collect on said ioor.

IOO

IIO

I do not broadly claim a depending watercirculating tube.

the combustion-chamber and been irregularly set; but in that class of steam-generators the products of combustion do not have a continuous flow horizontally, or substantially so, or toward one end of the combustion-chamber to one uptake, so as to form a continous current, such as it is herein aimed to interrupt by staggering the tubes, as set forth.

It will be noticed that the generator-shell herein described is made of wrought metal, suitably flanged to be united together and to the metallic outer casing of the combustionchamber; whereas if said shell were composed of cast metal it could not be adapted for locomotive-engines. because of its great weight, liability to crack from unequal expansion, and lack of strength for steam at high pressure.

Having thus described my invention, I claiml. In a steam-generating apparatus, the rebox A and combustioirchamber B, in combination with the wrought-metal fiattened concaved generator-shell D, arranged to cover the combustion -chamber, as shown, and watertubes connected with the attened Linder side of the said shell, substantially as described.

2. The combination, with the shell, of the outer tubes, inner tubes, and tubular nut and the stay-bolts, to operate substantially as described.

3. In a steam-generator, the tubular nut provided with the screwthreaded part to enter the generator-shell, and the openings and waterways, combined with the thin outer tube, brazed or permanently attached to the said nut, and theinner tube, i, attached to the said nut, substantially as shown.

4. The combination of thetubularnutF, provided with openings I. m, the stay-bolt 7L, secured to the top of the nut, and the tubes E and z', all arranged for the purposes set forth.

5. In a steam-generator, the elongated horizontally-placed concaved wrought-metal shell, the combustion-chamber covered by the said shell, the fire-box at one end of the combustion-chamber and shell, and the uptake at the other end of the combustion-chamber and shell, as explained, combined with the pendent water-tubes E, attached to the said shell at its under side between its ends, and arranged in rows across the track of the flames and gases passing horizontally along under the shell to its front end and into the uptake, the tubes in each row being arranged opposite the spaces between the tubes in the adjoining row or rows, so that the body or column of flame and gases flowing to the uptake is broken up to utilize to the highest degree the heat of all parts of the ame and gases directly upon the tubes, substantially as set f'orth.

6. The combination of the generator-shell D and pendent water-tubesE,constructed and arranged as shown, with the re-box A, the combustion-chamber B, and the lateral deflectors o o, all arranged substantially as set forth.

7. rIhe flattened wrought-metal generatorshell D .and the pendent water-tubes connected therewith, substantially as described, combined with the metal casing for the combustion-chamber and the refractory lining for the fire-box and entire casing up to the shell, the

fire-box portion of the metal casing being made narrow, as set forth and shown, to rest between the drivers, leaving the upper widened portion of the casing from end to end to receive the tubes, thus increasing the re-surface, substantially as described.

8. The combination of the rectangular casing of the furnace, lined with lire-brick or tiles, with the rectangular flattened shellD, having a peripheral median flange arranged to rest upon the said casing, and the interposed refractory material c, substantially as and for the purpose set forth.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

FRANK M. STEVENS.

Witnesses:

HENRY GoNNE'rr, ARTHUR C. FRASER. 

